The invention relates to a silver halide color photographic light-sensitive material, and further detailedly relates to a silver halide color photographic light-sensitive material excellent in color reproducibility.
The formation of a dye image with use of a silver halide color photographic light-sensitive material is made usually by that, when a color developing agent of aromatic primary amine type reduces silver halide grains in the exposed silver halide color photographic light-sensitive material, it is oxidized, and that then the oxidation product forms the dye by the reaction with a coupler preliminarily contained in the silver halide color photographic light-sensitive material. As coupler, 3 couplers which can form yellow, magenta and cyan dyes, respectively, are usually utilized because the color reproduction is carried out by a substractive process. However, any of actually utilized couplers is not ideal in view of its color reproducibility, and the spectral apsorptive properties of its color developing dye is largely different from the optimal ones, and especially the incorrect absorption of the dye leads to the decrease in reproduction of hue and saturation.
Among these couplers, for the purpose to form a magenta dye image, there are employed couplers of 5-pyrazolone, cyanoacetophenone, indazolone, pyrazolobenzimidazole, or pyrazolotriazole type.
Most of couplers conventionally utilized to form the magenta dye image have been those of 5-pyrazolone type. Whereas the dye image formed by such a coupler of 5-pyrazolone type has an advantage of light and heat fastness, in view of spectral absorptive properties it has shortcomings that the color tone is poor with an incorrect absorption having a yellow component at about 430 nm, and an unsharp foot on the longer wave side, causing color muddiness, and that the color developing dye image formed therefrom also is poor in sharpness.
These shortcomings are especially problematical for a directly observed color print which carries an image on its reflective support.
As couplers not accompanying such an incorrect absorption, couplers of pyrazolotriazole type are especially excellent which have been described in, for example, U.S. Pat. No. 3,725,067; Japanese Patent Examined Publication No. 99437/1984, 162548/1984, or 171956/1984; or Research Disclosure No. 24220, 24230, or 24531. Any of these couplers is effective in red and blue color reproduction by the substractive color reproducing process, because it has little incorrect absorption around 430 nm, and a sharp foot on the longer wave side.
Furthermore, the improvement of the color reproducibility is one of the most important technical subjects in a recent color light-sensitive material in which a high quality image is required, expecially in a printing color light-sensitive material which is printed from a color negative film. As for criteria of color reproduction in the photographic engineering, there are described, in detail, in "Fundamentals of Photographic Engineering. Silver Salt Photography", edited by Society of Photographic Science and Technology of Japan, p. 404-413, (Jan. 30, 1979). Especially in the case of the above printing color light-sensitive material, it is one of points how both the hue and the saturation of a chromatism are reproduced when an achromatism is reproduced as it is.
One the other hand, the recent age demands a high-sensitivity in a silver halide photographic light-sensitive material, from various viewpoints, and diverse technological studies on sensitization are in progress.
Concerning studies of sensitization improvement on silver halide grains, for example, a work on theoretical calculation of quanum efficiency of a silver halide under consideration of the effect of a grain size distribution is described in the preprint for the symposlum, Tokyo, 1980 on the progress in photography, "Interactions between Light and Materials for Photographic Applications", p. 91. This description suggests that the formation of a monodispersed emulsion is effective on the improvement of the quantum efficiency, or, of high sensitization. On the other hand, the optimal chemical sensitization of such silver halide emulsion also is under investigation to improve sensitization technology. As sensitizers used in chemical sensitization, there are conventionally well-known sulfur, selenium, reduction or noble metal sensitizers. Each of these chemical sensitizers is used either singly or in combination of two or more sensitizers. In addition, various methods have been studied to further raise the effect of such a chemical sensitization, including the method to chemically sensitize silver halide grains in the presence of a solvent for a silver halide (as disclosed in Japanese Patent O.P.I. Publication No. 30747/1983), or in the presence of a nitrogen-containing heterocyclic compound which forms a complex with silver (as described in Japanese Patent O.P.I. Publication No. 126526/1983).
Furthermore, it is also well-known to spectrally sensitize a silver halide emulsion by widening the range of the light-sensitive wave length inherent in the silver halide emulsion through adding a sensitizing dye. It is also known that appropriately selecting a sensitizing dye which is high in its efficiency of spectral sensitization remarkably contributes to elevation of sensitivity of the light-sensitive material.
As a sensitizing dye used for the above purpose, there is selected a sensitizing dye which is appropriate in its range of wave length of spectral sensitization, and exhibits neither diffusion to other light-sensitive layers nor interaction with other additives. Especially in case of making use of a sensitizing dye in a multilayered color photographic light-sensitive material, the one with both a further high sensitivity and an excellent color reproducibility is demanded.
Among spectally sensitizing methods as above-described, means to spectrally sensitize the range of blue color are described in, for example, U.S. Pat. Nos. 3,480,434 and 3,752,670; West german Patent OLS Application No. 2,303,204; and Japanese Patent Examined Publication No. 30023/1971, but a sensitizing dye is especially effective which can color sensitize a silver halide so that the maximum value of the spectral sensitivity by the color sensitization may come out to a range of wave length not less than 450 nm and less than 500 nm.
However in the conventional color reproduction when an image is printed from a printing multilayered color light-sensitive material using a blue-sensitive silver halide emulsion which was color sensitized as above-described and has a maximum value of spectral sensitivity in a range of wavelengths not less than 450 nm and less than 500 nm, the reproduction of green hue gets out of position toward cyan, resulting in a drawback of bluish green reproduction for green color, when the achromatism is reproduced as it is achromatic. Therefore, it has been demanded to develop a printing multilayered silver halide color photographic light-sensitive material which is high in its blue sensitivity and excellent in its green color reproducibility.